Properties of Commercial Conductive Floorings for Hospital Operating Rooms

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Research Paper (National Research Council of Canada. Division of Building Research); no. DBR-RP-25, 1956-08-01

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Properties of Commercial Conductive Floorings for Hospital Operating Rooms

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NATIONAL RESEARCH COUNCIL CANADA

DIVISION OF BUILDING RESEARCH

PROPERTIES OF COMMERCIAL CONDUCTIVE FLOORINGS FOR HOSPITAL OPERATING ROOMS

b y P . J . S e r e d a R e s e a r c h P a p e r No. 2 5 o f t h e D i v i s i o n o f B u i l d i n g R e s e a r c h O t t a w a S e p t e m b e r

1956

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PROPERTIES OF COMMERCIAL CONDUCTIVE FLOORINGS FOR HOSPITAL OPERATING ROOMS

P . J . Sereda

It i s now g e n e r a l l y accepted t h a t t h e f l o o r s of h o s p i t a l o p e r a t i n g rooms should be e l e c t r i c a l l y semi-

conducting t o prevent t h e accumulation of e l e c t r o s t a t i c c h a r g e s , A d i s c u s s i o n of t h e problem involved and of t h e r e a s o n s f o r t h e use of conductive f l o o r i n g has been g i v e n i n a paper by Legget and Sereda ( 1 ) .

Since t h e demand f o r conductive f l o o r i n g s a r o s e , a number of p r o d u c t s w i t h d i f f e r e n t g e n e r a l c h a r a c t e r i s t i c s have been made commercially a v a i l a b l e . These f l o o r s must perform t h e f u n c t i o n of o r d i n a r y f l o o r s i n a d d i t i o n t o

meeting t h e requirement of moderate e l e c t r i c a l c o n d u c t i v i t y . They a r e a l s o s u b j e c t t o t h e requirements of appearance, d u r a b i l i t y , and e f f e c t upon t h e comfort and convenience of t h e u s e r . The s e l e c t i o n of a conductive f l o o r i n g , t h e r e - f o r e , depends upon t h e r e l a t i v e importance t o be a s s i g n e d t o t h e d e s i r e d p r o p e r t i e s , To a s s i s t i n t h e s e l e c t i o n of conductive f l o o r i n g f o r which s e r v i c e experience i s not a v a i l a b l e , and t o a s s e s s t h e p r o p e r t i e s of d i f f e r e n t

conductive f l o o r i n g s l a b o r a t o r y work was undertaken by t h e D i v i s i o n of B u i l d i n g Research.

Nine conductive f l o o r i n g m a t e r i a l s commercially a v a i l a b l e , e i g h t of them being p r o p r i e t a r y p r o d u c t s , have been under s t u d y i n t h e B u i l d i n g M a t e r i a l s Laboratory of t h e D i v i s i o n s i n c e J u l y 1954. Samples of t h e m a t e r i a l s s u f f i c i e n t t o make about

36

square f e e t of f i n i s h e d f l o o r were o b t a i n e d through normal channels and were used t o

c o n s t r u c t s m a l l t e s t a r e a s on t h e l a b o r a t o r y f l o o r . These have been s u b j e c t e d t o normal l a b o r a t o r y t r a f f i c ; t h e y have bean examined and c e r t a i n p e r t i n e n t p r o p e r t i e s

measured p e r i o d i c a l l y d u r i n g a p e r i o d of e i g h t e e n months. The r e s u l t s of t h e s e studhes a r e now r e p o r t e d .

EXPERIMENTAL WORK The f l o o r i n g s d e a l t w i t h i n t h i s i n v e s t i g a t i o n a r e l i s t e d under t h r e e g e n e r a l c a t e g o r i e s : ( i ) F l o o r c o v e r i n g s : Conductive v i n y l t i l e Conductive r u b b e r Conductive linoleum

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Conduct i v e c o a t i n g I @onduc.tive c o a t i n g 11 Conducti.ve c o a t i n g I11

Conduct l.ve s.esamic t i l e I @onductsl.ve aemnnic t l . l e JI

Condu-ctive t e m a z z o

A l l t h e s e . f l o o : ~ i n g m a t e r i a l s were i n s t a l l e d a c c o r d i n g t o m a n u f a c t u r e s ' s I . n s t r u c t i o n s and by s k i l l e d tradesmen where n e c e s s a r y , A l l the samples were i n s t a l l e d on t h e c o n c r e t e f l o o r in. t h e l a b o r a t n s y , 5.n s t r i p s 3 by

6

f e e t a s shown i n F i g . 1, ThSs S.r?.stal,l%tion was d u p l i c a t e d i n p a r t i n a n o t h e r sec.tSon. of t h e I . a b o ~ a t o r g ,

The f l o o ~ s we.m maintained by r e g u l a r washing w i t h w a t e r and d e t e r g e n t about twice weekly and dry-swept on a l t e r n a t e d a y s , On occasions t h e f l o o r s were scrubbed w l t h i n d u s t r i a l soap t o remove acsumulated o s embedded d i r t .

E l e c t s l c a l r e s i s t a n c e was measured soon a f t e r t h e f l o o r s were i . n s t a l . l e d 9 and a t s u i t a b l e i n t e r v a l s t h e r e a f t e r . Standard N.F.P,A, methnd of t e s t

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was followed and t h e e l e c t r o d e s were p?.aced.on t h e same a r e a s every time t h e t e s t was made,

I n d e n t a t i o n wa.s measured a f t e r s l x monthsr s e r v i c e u s i n g McBurneyls method

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The s l i p p e r i r . e s s was determined w i t h t h e S i g l e r S l i p p e r i n e s s T e s t e r

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a t s e g u l a r i n t e r v a l s .

Photomicrog~aphs were made of t h e s u r f a c e of a l l r e p r e s e n t a t i v e samples o f F l o o r i n g t o show s u r f a c e c h a r a c t e r -

i s t i c s and a r e reproduced I n P i g s . 2 t o

4.

DESCRIPTION OF FLOORS

Conductive Vinyl T i l e

T h i s t i l e was

9-

_by

9-

_{by 1/8-inch t h i c k . I t s c h i e f} c o n s t l . t u e n t was v i n y l p l a s t i c wfth a c e t y l e n e carbon black t o impart e l e c t r i c a l c o n d u c t f v i t y . I n s t a l l a t i o n ~ c o n s i s t e d of l a y i n g a s p e c i a l underl.ayment f e l t which c a r r i e d i t s own

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p r e s s u r e s e n s i t i v e a d h e s i v e on b o t h f a c e s t h u s s e r v i n g t o bond t h e f e l t t o t h e s u b f l o o r and t o bond t h e t i l e t o t h e f e l t , Conductive t a p e p l a c e d on a g r i d under t h e t i l e s provided e l e c t r i c a l i n t e r c o u p l i n g between t i l e s . The w h i t e and g r e e n m a r b l e i z e d p a t t e r n on b l a c k achieved t h e e f f e c t of h i d i n g t h e d i r t t r a c k i n g t h a t i s s o c h a r a c t e r i s t i c of b l a c k s u r f a c e s ,

Conductive Rubber

T h i s f l o o r i n g was purchased i n s t r i p s

3

f e e t wide and

118

i n c h t h i c k ; i t c o n s i s t e d of r u b b e r homogeneously compounded w i t h a c e t y l e n e carbon b l a c k . Each s t r i p had t h r e e copper w i r e s embedded i n t h e m a t e r i a l , e q u a l l y spaced and running t h e l e n g t h of t h e s t r i p . These p e r m i t t e d i n t e r - c o u p l i n g between s t r i p s . The s t r i p s of t h i s f l o o r i n g were bonded t o t h e base w i t h a d h e s i v e s i n t h e same manner a s f o r common f l o o r c o v e r i n g s ,

One of t h e c h a r a c t e r i s t i c s of t h i s t y p e of f l o o r i n g was t o p i c k up d i r t which became embedded i n t h e s u r f a c e . T h i s c o n t r i b u t e d , i t i s b e l i e v e d , t o t h e tendency of t h i s f l o o r i n g t o show an i n c r e a s e i n measured r e s i s t a n c e .

I n d i v i d u a l r e s i s t a n c e v a l u e s of 1 . 5 megohms have been r e c o r d e d , which d e c r e a s e d by a f a c t o r of t h r e e a f t e r t h e s u r f a c e was scrubbed w i t h i n d u s t r i a l s o a p , The u n i f o r m l y b l a c k s u r f a c e a c c e n t u a t e d t h e d i r t t r a c k s and s c u f f marks. Conductive Linoleum

T h i s c o v e r i n g was a v a i l a b l e a s 6 - f o o t wide s t r i p

material,

118

i ~ c h t h i c k , It was somewhat c h a r a c t e r i s t i c of o r d i n a r y l i n o l e u m c o v e r i n g s . I t s s u r f a c e was g r a p h i t i c i n appearance and f e e l , b e i n g somewhat s l i p p e r y and showing p o l i s h marks when rubbed, It was i n s t a l l e d d i r e c t l y on t h e c o n c r e t e f l o o r i n t h e same way a s t h e o r d i n a r y l i n o l e u m f l o o r c o v e r i n g s . It was n o t e d t h a t no p r o v i s i o n f o r e l e c t r i c a l i n t e r c o u p l i n g between s t r i p s was a v a i l a b l e

because t h e u n d e r s i d e of t h e s h e e t was non-conducting, and it was n o t a p p a r e n t how t h i s c o u l d be a c h i e v e d . I f t h e s h e e t s a r e l a r g e enough, i n t e r c o u p l i n g may n o t be n e c e s s a r y s i n c e each p i e c e would behave a s i t s own ground. The c h a r - c o a l g r e y s u r f a c e of t h i s m a t e r i a l d i d n o t show d i r t t r a c k s a s r e a d i l y a s d i d some o t h e r d a r k s u r f a c e s but t h e s u r f a c e

showed s c u f f marks r e a d i l y . These marks were removed d u r i n g washing o p e r a t i o n s , G r a p h i t e - l i k e f l a k e s of t h e m a t e r i a l could be rubbed o f f t h e s u r f a c e of t h i s l i n o l e u m .

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Conduct i v e Coating I

T h i s was a ccnductive caateng of p a i n t - l i k e c o n s i s t e n c y which was a p p l i e d on t h e s u r f a c e of 1/8-inch cement-asbestos board and t h e n l a i d on a c o n c r e t e b a s e . The c o a t i n g was appl.ied i n a x a m b e ~ af c o a t s t o a t h i c k - n e s s of about 1/16 S.nch, The resulting c o a t i n g was f a i r l y hard and had a s h i n y b l a c k finish, Thfs c o a t i n g appeared t o s t a n d up t o t r a f f i c and ,yl.aintena~cs r e a s o n a b l y w e l l , The manufacturer recommended t h e use sf a s p e c i a l p o l i s h t o p r e s e r v e t h e c.oati,ng, When t h i s p o l i s h was used t h e F l o o r i n g became t o o slippery f ~ r comfostsble walking, Conductive Coating I1

T h i s c o a t % n g was a v a i l a b l e %w _{t h r s e c o l s u r s : g r e y ,}

g r e e n , and brown, It ~ . s n s f s t e d 0% graded s a n d p s p e c i a l

bonding m a t e r i a l and pLment, It was s u p p l i e d as a p l a s t i c mix, t h i n n e d t o %%owell$I?ig c o n s i s t s ~ s ~ ~ which was t r o w e l l e d

i n thicknesses of about

l/e

inch on t o t h e cowcrete f l o o r i n s t r i p s about i by

5

f e e t , A s e a l e r s u p p l i e d by t h e manufacturer was t k e n a p p l i e d on t h e s u r f a c e . The samples made up i n t h e l a b o r a t o ~ y remainad s o f t For about a week, They d i d f i n a l l y harden i n t o a r e a s o n a b l y hard f l o o r . The

c o ~ s i s t e n c y ~f t h e mix was n o t t h e b e a t f o r good t r o w e l l i n g

and t h e surface afftes t r o w e l l i n g was t h e r e f o r e not v e r y

s8mooth. T h i s LuzeTlerGness made @?.aanfng opepat i o n s d i f f i c u l t , .mBy be t h a t a b e t t e - j o b could t a v a been done by a man experienced i n t&>e a p p l i c d t l o r ~ of t h t s m a t e r i a l ,

Conductive Coatina

III

T h i s rnaterd.al was a f l o s s c o a t i n g t o be a p p l i e d t o e x i s t i n g f l o o r s u r f a c e s i r s th1.c-knesses of about 3/16 i n c h . T h i s m a t e r i a l c o n s i s t s c h l e f l y o f r u b b e r l a t e x and p s r t l a n d

cement w i t h o t h e s a d d i t i v e s t o g i v e t h e m a t e r i a l a measure of e l e c t r i c a l c o n d u c t i v i t y , M p r o p r i e t a r y s e a l e r was used t o s e a l t h i s f l o ~ r , The appearance of' t h i s f l o o r i n g was somewhat poor but t h i s may have been p a r t l y due t o t h e f a c t t h a t t h e a p p l i c a t i o n was n o t done by a n experienced t r a d e s - man, The m a t e r i a l d i d n o t have t h e c o n s i s t e n c y f o r e a s y

t r o w e l l i n g and i t s e t r a p i d l y , Al.though t h e s u r f a c e was s e a l e d , t h e c o a r s e t e x t u r e of t h e s u r f a c e was d i f f i c u l t t o keep c l e a n , The n a t u r e of t h e s l a ~ f a c e of t h i s m a t e r i a l i s such t h a t s h a r p o b j e c t s can t e a r i t . T h i s i s shown i n t h e photomicrograph of t h e s c m t c t hardness t e s t ( F i g . 3 ( c ) ) .

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Conductive Ceramic T i l e B

These d a r k brown t i l e s were 1-9/16 i n c h e s square by 1/4 i n c h t h i c k , They were l a i d i n a conductive adhesive on a c o n c r e t e f l o o r , A f t e r t h e adhesive had s e t , t h e j o i n t s between t i l e s were grouted w i t h cement m o r t a r . I n new

c o n s t r u c t i o n t h e s e t i l e s would be l a i d i n a m o r t a r underbed c o n t a i n i n g 3 p e r cent a c e t y l e n e b l a c k , T h i s i n s t a l l a t i o n of f l o o r i n g r e s u l t e d i n a hard and s e r v i c e a b l e f l o o r s u r f a c e . The t i l e i t s e l f WELS t h e h a ~ d e s t OF any of t h e f l o o r i n g m a t e r i a l s

t e s t e d . The diamond p o i n t i n t h e s c ~ a t c h t e s t d i d n o t make a v i s i b l e mask ( F i g . 51,

Conductive Ceramic T i l e

%I

T h i s f l o o r i n g c o n s i s t e d of condgctfve ceramic t i l e s 3/4 i n c h square and 114 i n c h t h i c k , dark brownish-black i n

c o l o u r , a l t e r n a t e d w i t h gpeen ceramic non-conducting t i l e s 318 by 3/4 i a c h , The t i l e s were l a i d i n a conductive adhesive on t h e e x i s t i n g c ~ n c r e t e f l o o r , The j o i n t s between t i l e s were grouted w i t h a cement m o r t a r . I n new c o n s t r u c t i o n t h e s e t i l e s would be l a i d i n a conductive m o r t a r underbed c o n t a i n i n g 3 p e r

c e n t a c e t y l e n e b l a c k , T h l s t i l e was as hard a s t h e Conductive Ceramic T i l e I and e q u a l l y a s s e r v i c e a b l e , A sample of t h i s t i l e f l o o r i n g l a i d i n m o r t a r underbed was t e s t e d f o r r e s i s t a n c e t o w e t t i n g w i t h a l k a l i n e d e t e r g e n t s , A f t e r 4000 c y c l e s of wet- '

ting w i t h 0 , 5 pey c e n t s o l u % f o n of t r i s o d f m phosphate and p a r t i a l d r y f c g t h e r e w a s no s e r i o u s break-up of e i t h e r t h e t i l e s o r t h e m o r t a r ,

Conductive T e r r a z z o

T h i s mater'al wk.icka w i l l normally be c o n s i d e r e d f o r new c o n s t r u c t i o n only, c o n s i s t s of a c a s t topping of marble

c h i p s and p o r t l a n d cement w i t h a c e t y l e n e carbon. T h i s ,bopfiing i s u s u a l l y l a i d on a p r e p a r e d mortar bed c o n t a i n i n g a c e t y l e n e carbon b l a c k . D e t a i l e d s p e c i f i c a t i o n s f o r l a y i n g t h i s f l o o r a r e a v a i l a b l e and need n o t be r e p e a t e d h e r e . The p h y s i c a l p r o p e r t i e s of t h i s f l o o r i n g a r e comparable t o ceramic t i l e

i n some r e s p e c t s a l t h o u g h both t h e marble and t h e cement

m a t r i x a r e s o f t e r t h a n t h e ceramic t i l e . Photomicrographs of t h e s c r a t c h t e s t show t h a t t h e marble c h i p s a r e h a r d e r t h a n t h e m a t r i x ( F i g , 4 C a ) ) . T e r r a z z o samples were n o t i n c l u d e d o r i g i n a l l y i n t h e s e r i e s of samples d e s c r i b e d i n t h i s r e p o r t . Various a s p e c t s of t h i s t y p e of f l o o r i n g were i n v e s t i g a t e d u s i n g samples of t e r r a z z o f l o o r i n g measuring 9 by

18

by 3/4 i n c h . Some of t h e p h y s i c a l p r o p e r t i e s r e p o r t e d i n t h e t a b l e s

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a r e based on t e s t s conducted on t h e s e samples, R e s u l t s of o t h e r i n v e s t i g a t i o n s dealCng w i t h t h e s p e c f a l problems of t h e s e cementl.t.foi~s m a t e r % , a l s w.-P,11 be r e p o r t e d s e p a r a t e l y , PHYS I C A L PROPERTIES

Table I l i s t s average values F o r t h e v a r i o u s p h y s i c a l p r o p e r t l . e s t h a t were meassa~ed, I n a l l c a s e s t h e s e v a l u e s a p p l y t o t h e samples urndexa t e s t , S i w e only one sample of each type was purchased9 it is n o t c e ~ k a 2 n _{t h a t t h e s e a r e t r u l y r e p r e s e n t a -}

t i v e of t h e m a t e r i a l s slmlla$le on t h e market, CRITERIA FOR T-FiE SEUCTIQN OF COATDUGTIVE FLOORS

A conduct%ve f l o o r mast meet t h e requirement of moderate e l e c t r i c a l conductl.vLty, S ~ c h a f l o o r must, i n a d d i t i o n , perform t h e f u n c t i o n of any o r d i n a r y f l o o r and t h u s i s s u b J e c t ko a d d i . t i o n a l requirements of appearance, d u r a b i l i t y , and e f f e c t on t h e comfost and convenience of t h e u s e r . The requirements f o r appearance and d u r a b i l i t y a r e r e l a t e d , The a e s t h e t i c C e a t u r e s of t h e f l o o r , a l t h o u g h i n t h e f i r s t i n s t a n c e dependent upon c o l o u r , p a t t e r n and t e x t u r e , as w e l l a s t h e e a s e w i t h wh.l,ck it. can be kept c l e a n , a r e

u l t i m a t e l y dependent a l s o on t k , s du- ability of t h e f l o o r

f i n i s h . The d u r a b i l i t y of t h e rlooin f l . n i s h i s r e l a t e d t o t h e wearing p r o p e r t y , t h e ~ e s i s t x n c e t o permanent i n d e n t a t i o n , and

t h e degree of scufC1,ng ama ma-sing t h a t occur w i t h f o o t t r a f f i c . The r e q u l r e m e ~ t f o r comfort 1 s _{? e l a t e d t o %he p r o p e r t i e s of}

warmth, q u i e t n e s s

,

aizd non-slipperFfiess, The p r o p e r t i e s of f l o o r i n g e s s e n t z a l f o r comfort mag the-efo-e be opposed t o t h e p r o p e r t i e s e s s e n t i a l t o meet t h e ~ e y u i s e m e n t s of' d u r a b i l i t y ,

The requirement ~ Q F xn.0de:ca.t.e e l e z f u r i c a l c o n d u c t i v i t y

i s d e f i n e d by N.F,P,A, B u l l e t i n

56

( 3 ) i n terms of r e s i s t a n c e l i m i t s , a c c o r d i n g t o a d e s i g n a t e d t e s t , I n t h e work under review an a d d i t i o n a l t e s t was i n c l u d e d t o show t h e e f f e c t of moisture on t h e surface of t h e f l o o r , T h i s was measured by

moistening t h e a r e a of t h e f l o o r under t h e e l e c t r o d e s . It could be argued t h a t t h e lower l i m i t of r e s i s t a n c e should be met under t h i s s p e c i a l c o n d i t i o n becauses under normal c o n d i t i o n s , t h e f l o o r i n a n o p e r a t i n g room may be wet due t o s p i l l a g e .

There i s l i t t l e choice i n t h e m a t t e r of s e l e c t i n g conductive f l o o r s on t h e b a s i s of appearance a l o n e s i n c e most of t h e a v a i l a b l e f l o o r i n g m a t e r i a l s a r e b l a c k , d a r k g r e y , o r brown, There i s , however, a c o n s i d e r a b l e d i f f e r e n c e i n t h e e a s e w i t h which t h e d f f f e ~ e n t f l ~ ~ r s can be kept looking

(11)

neasonably c l e a n . Some m a t e r i a l s r e q u i r e waxing t o keep tke s u r f a c e i n good c o n d i t i o n ; s i n c e s u i t a b l e condu-ctive waxes a r e n o t y e t a v a i l a b l e t h e s e m a t e r i a l s a r e p l a c e d a t a consZCs:?- a b l e d i s a d v a n t a g e ,

Although over t h e y e a r s a v a r i e t y of t e s t s have beer* d e v i s e d t o measure a b r a s i o n r e s i s t a n c e a s a p o s s i b l e index cg d u r a b i l i t y , i t i s g e n e r a l l y agreed t h a t t h e s e t e s t s can sesve t o r a t e m a t e r i a l s of one c l a s s o n l y , Thus a b r a s i o n t e s t s vac-e r ~ o t included i n t h i s i n v e s t i g a t i o n . Observations a r c ke-ing made of t h e degree of wear of t h e samples exposed t o f o o t t s a f f i c

.

Where i t i s thought n e c e s s a r y

,

s p e c i a l labc~at~o-:( t e s t s a r e being conducted t o expose samples t o s p e c i f i c

~ : o n d i t i o n s , such as t h e e f f e c t of a l k a l i n e d e t e r g e n t s xpcn c a m e n t i t i o u s f l o o r i n g l i k e t e r r a z z o .

The r e s i s t a n c e of t h e f l o o r i n g t o i n d e n t a t i o n was measu-red by means of a McBurney I n d e n t a t i o n T e s t e r

(4-1,

The

v a l u e of t h e r e s i d u a l i n d e n t a t i o n i s a n i n d i c a t i o n of t h e

r e s l . s t a n c e t o permanent deformation due t o a c o n c e n t r a t e d Load such a s t a b l e l e g s o r c h a i r l e s

.

I n a d d i t i o n , t h e 'Saber S:::r~a:tck-r. T e s t e r was adapted t o a l l o w p r e c i s e measurements t o be ~ a d e oP t h e s c r a t c h width made by a diamond p o i n t a t v a r i o u s l o a d s , Values were o b t a i n e d by measuring t h e s c r a t c h w i d t h on photomicrographs. It i s thought t h a t t h i s value r e l a t e s t o t h e e x s e

w i t h which. t h e f l o o r sv-rface can be s c u f f e d and m.a>rred by a b r a s i v e m a t e r i a l c a r r i e d on shoes. There i s no b a s i s a t

p r e s e n t by which t h e s e v a l u e s can be r e l a t e d t o a c t u a l serv.l,ci-: s o t h a t t h e y can s e r v e as an. i n d i c a t i c n only of r e s i s t a n c e 'LC?

s c r a t c h i n g .

Generally speakings t h e f a c t o r s a f f e c t i n g t h e ~ o - ~ c : c ~

of a person on a given f l o o r namely warmth, q u i e t n e s s , am3 Y ~ C < > -

s l i p p e r i n e s s , a r e o f t e n r e l a t e d t o t h e r o p e r t y of r e s i l i z n c c of t h e f l o o r . Thus t h e i n i t i a l (1 min.

7

indentation v a l u e s c a r

t h e s c r a t c h width can s e r v e a l s o a s i n d i c a t o r s of comfort, It

w i l l be apparent t h a t t h e d e s i r a b l e p r o p e r t y of f l o o r i n g i n terms of comfort can a t t h e same time be u n d e s i r a b l e i n terzi:: of d u r a b i l i t y .

The p r o p e r t y of s l i p p e r i n e s s a s i t r e l a t e s t o cornXo~t was measured by means of t h e S i g l e r S l i p p e r i n e s s T e s t e r

(51,

The valuesgiven i n Table I a r e r e a l l y v a l u e s f o r t h e c o e f f l . e i s a t of f r i c t i o n between t h e f l o o r s u r f a c e and a l e a t h e r h e e l . It i s considered t h a t a s u r f a c e having an a n t i - s l i p c o e f f i c i e n t a b c v e 0.40 can be c l a s s e d a s n o t s l i p p e r y . Values of a n t i - s l i p

c o e f f i c i e n t of 0.3 t o 0.4 a r e c o n s i d e r e d t o d e f i n e a r e a s o n e ~ l , ~ s a f e f l o o r . The v a l u e s g i v e n i n Table I a r e c o e f f i c i e n t s f o r

(12)

l e a t h e r w i t h t h e v a r i o u s f l o o r sla?faces, If a r u b b e r h e e l had been used, t h e c o e f f i . c i e n t s would have been much h i g h e r -unless t h e f l o o r was w e t ,

Waxes and p o l i s h e s a f f e c t t h e s l i p p e r i n e s s of a s u ~ f a c e t o a c o n s f d e r a b l e d e g r e e . Since conductive f l o o r s normally a r e n e i t h e r waxed nos p o l i s h e d 9 t h i s c o n s i d e r a t i o n

i s of concern only i n d i r e c $ l y , i n t h a t wax can be t r a c k e d from one f l o o r t o a n o t h e r , It i s w e l l known t h a t a s l i p p e r y a r e a of f l o o r a d j o i n i n g a c o n - s l i p p e r y a r e a can be a g r e a t e r hazard t h a n i f a l l th,e a?ea i s ~ ~ a i f o r m l ~ r s l i p p e r y , T h i s p o t e n t i a l hazard can e x i s t I n an o p e y a t i n g s u i t e where t h e

area of conductive f l o o s f . r , g may be l e s s s l i p p e r y t h a n a d j o i n i n g h a l l f l o o ~ s ~ ~ h 2 . c h may have been waxed,

SUNMARY AND CONCLUSIONS

A comparison of t h e p r o p e r t i e s of d i f f e r e n t conductive f l o o r i n g m a t e r i a l s 'belonging t o one c l a s s i s p r e s e n t e d i n Table 11, f o l l o w i n g t h e method used by Llewellyn and Harper ( 2 ) . It should be remembered t h a t each symbol r e p r e s e n t s not a d e f i n i t e g r a d i n g but t h e average of a sange based l a r g e l y on p e r s o n a l Judgment. It must a l s o be noted t h a t t h i s comparison i s based o n l y on t h e samples und-er I n v e s t i g a t i o n . It i s n o t known what v a r i a t i o n s may be encountered w i t h d i f f e r e n t b a t c h e s of t h e v a r i o i ~ s m a t e r i a l s laor what q u a l i t y ccjntrol i s e x e r c i s e d i n t h e i r manufacture and l . r t s t a l l a t l . o n . There i s a pos,.i,ibility t h a t t h e p r o p e r t i e s of a t l e a s t some of t h e s e f l o o r i n g m a t e r i a l s may v a r y w i t h t h e s u b f l o o r on whfch t h e y a r e l a i d . For example, t h e i n d e n t a t i o n v a l u e s f o r t h e conductive v i n y l t e s t e d d i r e c t l y on c o n c r e t e d i f f e r from t h o s e o b t a i n e d w i t h t h e same t i l e l a i d w i t h underlayment f e l t . I n t h e l a t t e r c a s e , t h e l a r g e r apparent i n d e n t a t i o n i s due t o t h e d e f l e c t i o n of t h e base and does not a c t u a l l y r e s u l t i n an i n c r e a s e d permanent deformation of t h e s u r f a c e .

It can be seen from Table 11 t h a t t h e group of m a t e r i a l s which r a t e hfgh i n t h e d e s i r a b l e p r o p e r t i e s from t h e s t a n d p o i n t of appearance and d u r a b i l i t y , s a t e low i n t h e p r o p e g t i e s r e l a t i n g t o comfort. The r e v e r s e i s t r u e i n t h e c a s e of t h e group of' m a t e r i a l s which r a & e h i g h i n comfort. It may be suggested t h a t co-mfo~t i s an important c o n s i d e r a t i o n when s e l e c t i n g f l o o r i n g m a t e r i a l s . When a d e c i s i o n i s t a k e n t o i n s t a l l a n o n - r e s i l i e n t type of f l o o r i n g 9 which r a t e s low i n comfort, c o n s i d e r a t i o n should alviays be g i v e n t o t h e type of' footwear which w i l l be used s i n c e i t should be Qossible t o a t t a i n t h e d e s i r a b l e degree of comfort by t h e proper s e l e c t i o n of shoes.

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Photomicrographs of t h e s u r f a c e of t h e v a r i o u s c o n d u c t i v e f l o o r i . n g m a t e r i a l s t e s t e d a r e i n c l u d e d t o show t h e t e x t u r e and m i c r o s t . ~ u c t u r e of t h e s e s u r f a c e s , These s h o u l d a i d i n a s s e s s i n g some of t h e c h a r a c t e r i s t i c s of t h e f l o o r i n g m a t e r i a l s , The w i d t h and c h a r a c t e r of t h e marks of t h e s u r f a c e s and b.omogeneity of t h e m a t e r i a l , The w i d t h s of t h e s e s c r a t c h marks as r e l a t e d t o t h e 1oadi.ng on t h e diamond p o i n t a r e p l o t t e d i n P i g , 5 ,

It shou1.d be n o t e d f i n a l l y that d i s c . u s s i o n of t h e c o s t of matesia1.s b a s n a t u z a l l y been o m i t t e d from t h i s r e p o r t . Cost is n e v e r t h e l e s s a n fmport.ant c o n s i d e r a t i o n when s e l e c t i n g

f l.oo~ir?.g but one which n u s t be l e f t f o r a s s e s s m e n t i n t h e l i g h t of a l l t h e f a c t o r s which have t o be c o n s i d e r e d i n e a c h e a s e . ACKNOWLEDGMENTS The p ~ o j e c t d e s c r i b e d . by t h i s r e p o r t was s t a r t e d by t h k s D i v i s i o n as a r e s u - l t of i n q u i r i e s r e c e i v e d from some @aa?.a.dian a r c h i t e c t s , and a f t e r c o n s u l t a t i o n w i t . h o t h e r b u i l d i n g r e s e a r c h o r g a n . i z a t i o n s . Throu-ghout t h e work t h e D i v i s i o n h a s been encou-raged a n d a s s i s t e d by a d v i c e from i n t e r e s t e d a r c h i - t e c t s and p a r t i c u l a r l y from M r , H O G , Hughes, C h i e f , H o s p i t a l Design D i v i s i o n of t k e Department of N a t i o n a l H e a l t h and W e l f a r e and f r o r n M r , J , G . L . Walden, Department of V e t e r a n s ' Affairs.

Tb.e work h a s been c a r p i e d o u t as a c o - o p e r a t i v e v e n t u r e between t h e D.i.vision of Radio and E l . e c t r i c a 1 Engineering and t h e D i v i s i o n of BuSlding R e s e a r c h . M r , A . R . Morse of t h e f o r m e r D i v i s i o n h a s been most h e l p f u l , A f t e r d i s c u s s i o n w i t h o t h e r b u i l d i n g r e s e a r c h o r g a n f z a t f ons it was found t h a t t h e problem of c o n d u c t i v e f l o o r i n g was of world-wide i n t e r e s t b u t one upon which work was n o t a p p a r e n t l y b e i n g conducted i n o t h e r c o u n t r i e s . T h i s r e p o r t w i l l , t h e r e f o m ? , be g o i n g t o o t h e r c o u n t r i e s of t h e

Commonwealth and t o t h e U n i t e d S t a t e s , f o r g e n e r a l u s e . The s t a f f of t h e N a t l o n a l B w e a u of S t a n d a r d s i n Washington i n p a r t i c u l a r have been most h e l p f u l , and f u r t h e r work of a co- o p e r a t i v e n a t u r e i s p l a n n e d .

The a s s i s t a n c e of t h e many members of t h e t e c h n i c a l s t a f f of t h e B u i l d i n g M a t e r i a l s S e c t i o n , DBR, p a r t i c u l a r l y of

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REFERENCES

(1) Legget, R.F, and P.J. S e r e d a . Conductive f l o o r s f o r s a f e t y i n h o s p i t a l s . J o u r n a l , Royal A r c h i t e c t u r a l I n s t i t u t e of Canada, November 1954? p.377-379. Also i s s u e d by t h e N a t i o n a l Research C o m c i l , Di.visLon of B u i l d i n g Research a s NRC 3467"

$ 2 ) Llewellyn, H O M O and F,C, Harper, F l o o r f i n i s h e s f o r houses and o t h e r n o n - i n d u s t r i a l b u i l d i n g s . Great B r i t a i n , D,S.I,R,, B u i l d i n g Research S t a t i o n , National. B u i l d i n g S t u d i e s , B u l l e t i n No, 11, 20 p , ( 3 ) Recommended s a f e p r a c t i c e f o r h o s p i t a l o p e r a t i n g rooms, N,F.P.A. No,

56

of t h e N a t i o n a l F i k e P r o t e c t i o n A s s o c i a t f o n , Boston, 40 p . ( 4 ) McBurney, J , W , I n d e n t a t i o n of a s p h a l t t i l e , A,S,T,M, Proceedings, v o l , 34, p t , 11, p,591-602, 1934

( 5 )

S i g l e r , P.A., M O H O Geib and T . H , Boone, Measurement of t h e s l i p p e r i n e s s of walkway s u r f a c e s . U,S

.

Bureau of S t a n d a r d s ? J o u r n a l of Research, v o l . 40, no.

5 ?

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TABLE I F l o o r i n g and Base Conductive Vinyl T i l e i n a d h e s i v e on c o n c r e t e on f e l t underlayment Conduct i v e Rubber i n a d h e s i v e on c o n c r e t e Conductive Linoleum i n a d h e s i v e on c o n c r e t e Conduct i v e Coating I on 1/8 i n . t r a n s i t e Conduct i v e Coat i n g I1 on c o n c r e t e

Conductive Coat i n g I11

on c o n c r e t e Conductive Ceramic T i l e I i n an a d h e s i v e on c o n c r e t e Conductive Ceramic T i l e I1 i n a n a d h e s i v e on c o n c r e t e Conductive Terrazzo*** -

PIlYSICAL PROPERTIES OF CONDUCTIVE FLOORING COVNERCIALLY AVAILABLE I N 1554

- -

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TABLE I1

COMPARISON OF PROPERTIES OF FLOOR FINISHES COMMERCIALLY AVAILABLE IN 1954

Appearance and D u r a b i l i t y

R e s i s t a n c e t~

Ease of Inden-

M a t e r i a l Colour Range C l e a n i n g t a t i o n Wear

Coverings Conductive V i n y l T i l e ( 1 9 5 4 i

:,!,:I:

I

F-G G P-F F-G I I E l e c t r i c a l R e s i s t a n c e I I d e a l Extreme F-G

I

P Notes t o T a b l e 11: The l e t t e r s i n t h e T a b l e r e f e r t o t h e f o l l o w i n g : -- VG - v e r y good G - good F - f a i r P - poor VP - v e r y poor

Ease of C l e a n i n g : The a s s e s s m e n t i n c l u d e s d i r t r e t e n t i o n , t h e f r e q u e n c y of maintenance r e q u i r e d t o

--

m a i n t a i n t h e o r i g i n a l a p p e a r a n c e , and t h e e f f o r t r e q u i r e d i n t h a t m a i n t e n a n c e . R e s i s t a n c e t o I n d e n t a t i o n : T h i s r e l a t e s t o t h e r e s i s t ' a n c e t o permanent d e n t i n g caused b j f u r n i t u r e . R e s i s t a n c e t o Wear: T h i s column a s s e s s e s t h e performance i n use a t t h e end of e i g h t e e n months'

f o o t t r a f f i c .

Q u i e t n e s s : By q u i e t n e s s i s meant t h e a b s e n c e of n o i s e n u i s a n c e produced on t h e o c c u p a n t s by t h e i r movements w i t h i n t h e room.

E l e c t r i c a l R e s i s t a n c e : Extreme c o n d i t i o n s - t h i s a s s e s s e s t h e change i n r e s i s t a n c e when t h e s u r f a c e of t h e f l o o r i s w e t t e d w i t h w a t e r .

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F i g , 2 ( a )

F i g . 2 ( b )

Fig, 2 ( c )

F i g . 2 i , l i c r o y r a n h s o f t h e s u r f ~ c e o f c o n d u c t i v e f l o o r c o v e r i n ~ s : _- ( a ) C o n d u c t i v e V i n y l T i l e ; ( b ) C o n d u c t i v e Linoleum; ( c ) C o n $ u c t i v e Rubber. I.Inrks o f s c r a t c h t e s t e r , ma,?, x

16.

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F i g .

303)

F i g . 3 ( c ) F i g .

3

I - l i c r o ; ~ r a ? h s of t h e s u r f a c e o f c o n d u c t i v e f l o o r c o a t i n g s : ( a ) C o n d u c t i v e Co:!ting I ; ( b ) C o n d u c t i v e C o a t i n g 11; ( c ) C o n d u c t i v e C o a t i n g 111. lelarks o f s c r a t c h t e s t e r , map. x 1 6 . NHC 4 0 3 1

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F i g , b . ( b )

F i g .

4

P l i c r o g r a p h s o f t h e s u r f a c e o f c o n d u c t i v e c a s t - i n - s i t u f l o o r i n g : ( a ) C o n d u c t i v e T e r r a z z o ;

( b ) C o n d u c t i v e Ceramic T i l e 11; ( c ) C o n d u c t i v e

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F i g . R e s u l t s of s c r a t c h t e s t C o n d u c t i v e C o c t i n g I11 C o n d u c t i v e Rubber Cond-ucti ve V i n y l T i l e C o n d u c t i v e Linoleum and C o n d u c t i v e C o a t i n g I C o n d u c t i v e C o s t i n g I1 C o n d u c t i v e Carbon T e r r a z z o ( P l a t r i x ) C o n d u c t i v e T e r r a z z o ( C a n a d i a n ' d h i t e i-larble C h i p s ) Cond.uctive Ceramic T i l e s I and I1